Sprint CEO Dan Hesse says moving forward, Spring will only offer unlimited data plans for smartphones. Other devices including smartphones being used to tether other devices will no longer have unlimited data. Also, the 3GB, 5GB, and 10GB data plans are still available, but those limits apply to both 3G and 4G simultaneously. Affected Sprint data usage will be calculated by the combined total of 3G and 4G use.

Overage charges equate to $0.5 per MB. Roaming data limits are also in place at either 100MB or 300MB depending on your plan, overage fees on roaming data is $0.25 per MB. Anyone paying the extra $20 per month for their smartphone Mobile Hotspot add-on (tethering) will now be seeing caps on tethered data use.

With the iPhone 4S unlimited data storm looming, are these changes just to get prepped? Analysts predict that Sprint’s promise of unlimited iPhone data will be short lived, just like Verizon before it.

Customers affected by these changes now have 30 days to cancel their contracts without being penalized by an early termination fee (ETF).